Add additional properties to display system info on ChromeOS

chrome/browser/extensions/api/system_info_display/display_info_provider.h

Index: chrome/browser/extensions/api/system_info_display/display_info_provider.h
diff --git a/chrome/browser/extensions/api/system_info_display/display_info_provider.h b/chrome/browser/extensions/api/system_info_display/display_info_provider.h
index b934da887043dcbcd7570e265d10826ada64a110..aab10c1cb4ed34e88eb1db52ff232752b713f35f 100644
--- a/chrome/browser/extensions/api/system_info_display/display_info_provider.h
+++ b/chrome/browser/extensions/api/system_info_display/display_info_provider.h
@@ -15,12 +15,23 @@ typedef std::vector<linked_ptr<
 
 class DisplayInfoProvider : public SystemInfoProvider<DisplayInfo> {
  public:
-  static DisplayInfoProvider* GetDisplayInfo();
+  typedef base::Callback<void(const DisplayInfo& info, bool success)>
+      RequestInfoCallback;
 
+  // Gets a DisplayInfoProvider instance.
+  static DisplayInfoProvider* GetProvider();
+
+  // Starts request for the display info, redirecting the request to a worker
+  // thread if needed (using SystemInfoProvider<DisplayInfo>::StartQuery()).
+  // The callback will be called asynchronously.
+  // The implementation is platform specific.
+  void RequestInfo(const RequestInfoCallback& callback);
+
+ protected:
   // Overriden from SystemInfoProvider<DisplayInfo>.
+  // The implementation is platform specific.
   virtual bool QueryInfo(DisplayInfo* info) OVERRIDE;
 
- protected:
   friend class SystemInfoProvider<DisplayInfo>;
 
   DisplayInfoProvider() {}